Bug 19048

I'm not sure wether this is a real bug. This is more of a question if this
should be changed.

You can access listening demons bound to localhost from another machine
on the same ip subnet. Some people do not expect this. :)

Fix: 

filter 127/8 somewhere in the kernel?

if this is not deemed right, you can of course use ipfilter / ipfw to block
these packets.
How-To-Repeat: 
I'm on my host 'yoda'

| yoda:~#telnet 127.0.0.1
| Trying 127.0.0.1...
| Connected to localhost.
| Escape character is '^]'.
| 
| FreeBSD/i386 (yoda) (ttypa)
| 
| login:
| telnet> q
| Connection closed.

I modify the routes a bit...

| yoda:~#route delete -host 127.0.0.1
| delete host 127.0.0.1

| yoda:~#route add -host 127.0.0.1 -gateway kenobi
| add host 127.0.0.1

Now localhost is somewhere else :)

| yoda:~#telnet 127.0.0.1
| Trying 127.0.0.1...
| Connected to localhost.
| Escape character is '^]'.
| 
| FreeBSD/i386 (kenobi) (ttype)
| 
| login:
| telnet> q
| Connection closed.

I even tried it with program listening only on localhost:8888 on kenobi

| yoda:~#telnet 127.0.0.1 8888
| Trying 127.0.0.1...
| Connected to localhost.
| Escape character is '^]'.
| Hallo, hier ist kenobi-localhost
| Connection closed by foreign host.

Of course this usually doesn't matter because if you have bad guys on your
ethernet, you usually have worse problems already :)

But quite some people expect programs listening on localhost to be only
accessible from localhost.